Adjustable condenser



rL.. A. GEBl-ARD ADJUSTABLE CONDENSER Filed. Feb.

May 2, 1933.

I N VEN TOR.

V.. E N A) M T 1-- 1- 1-IQITT2----!! m a Q A/w QM e Q @w 4 .n 1 @w n. Lx :li: w i Cum k \l l r O ,if k P -:-:-i-:--- wm SQ. Q um v RNWVPatented May 2, 1933 UNITED STATES PATENT OFFICE LOUIS A. GECBHARD, 0FWASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO WIRED RADIO, INC., OF NEWYORK, N. Y., A CORPORATION 0F DELAWARE .ADJUSTABLE CONDENSER Applicationfiled February 1l, 1929.. Serial No. 339,144.

My -invention relates to adjustable condensei's'in general and moreparticularly to condensers employed in high frequency electiicalsignaling systems.

An object of my `invention is to provide an adjustable condenser whereinthe capacity is controlled easily and accurately within' desired limits.

Another object of my invention is to provide an adjustable condensercapable of withstanding high voltages.

Still another object of my invention is to provide an adjustablecondenser wherein eX- traneous electrostatic elds are eliminated fromthe condenser when such condenser is employed` in high power, highfrequencyv transmitters.

Other and further objects of my invention are to provide certainstructural features whereby the efciency of an adjustable condenser forhigh frequency, high power transmitters is increased.

'A better understanding of my invention can be had from thespecification following and from the accompanying drawing, wherein:

Figure l illustrates a front elevation in part section of the adjustablecondenser of my invention; Fig. 2 illustrates a side elevation in partsection of the adjustable condenserof my invention; and Fig. 3 shows a.view in section of `the upper plate structure taken on the lines 3 3 ofFig. l.

Adjustable condensers employed in high power and high frequencytransmitters must be of the design capable of withstanding veryhighlvoltages.. Such condensers must be adjustable over V,wide limits ofcapacity. lin addition, the insulation of the condenser must be such asto withstand the strain of very high frequencies. The metallic capacityplates must be of low resistance and capable of carrying large values ofcurrent without appreciable loss. A further desirable feature is thatthe condenser be shielded from extraneous electrostatic fields which arepresent in high power transmitters operating at high frequencies. Myapplication, Serial No.

327 ,990, filed December 22, 1928, shows a con.

denser similar to that described herein; the

' shows a front elevation in part section of the adjustable condenser ofmy invention. Adjustable plate structures 1l and 12 are electricallyconnected together and in combination constitute one capacity plate ofthe condenser. Plate structures'll and l2 are of suitable metal such asbrass or aluminum.

A convenient form of construction for plate structure 11 is shown inFig. l. Two vertical end members 7 of approximately rectangular sectionhave their outer corners well rounded and on their inner faces arerecessed to form a shoulderlportion as shown in F ig. 3. A bore 10 isprovided in each end member to receive actuating shaft 15. A plate 8 isbent in the shape of an inverted U forming two vertical sheets closed ontop by a curved portion which is the base of the The edges of each sheetlit into the shoulder recesses of end members 7 and are riveted orbolted thereto. rl`he interior of the Ll betweenend members 7 istherefore hollow and open below. The lower plate structure 12 mayconsist of a sheet folded about a forni such that it will take the formsimilar to that of the upper plate and having its bottom closed by basemember ll. There is a connection between the lower plate and the upperdue to the resiliency between the two plates. The sheets constitutingplate structures 11 and 12 may conveniently approximate a parallelrelationship.

Plate structure 12 is of slightly larger dimensions than plate structure11, the foi-mer adapted to slide over the latter. The slidingmovement ofstructure 12 over the surface of structure 11 is accomplished by theaction of a threaded shaft l5 engaging with a threaded bore in tube 5.Tube 5 is secured to plate structure 12 by means of a pin or screw 6.'ll'ube 5 moves vertically through bore l() in plate structure ll. Shaft15 rests in suitable bearings provided in member 14. Member 14 supportsgear mechanism 18, 19, 20, 21 and shafts 16 and 22. Shaft 15a. operatesina manner similar to the operation of shaft 15 and serves to divide thelifting vforce 100 in Fig. 1.

1 means of bevel gears between different portions of plate structure 12.Shafts 15 and 15a are turned by 18, 19, 20, 21and shafts 16 and 22.Supporting member 14 and plate structure 11 are held together in spacedrelationship'by tubular member andvbolt 17. The adjustable platestructures 11 and 12, together with the adjusting mechanism aresupported by insulating members 26. Insulating members 26 may be in turnsupported by the main framework of the transmitter. To prevent completeseparation of plate structures 11 and `12 some type of stop isnecessary. To restrict the movement of plate structure 12 within desiredlimits I provide a rod 1 extending the height of platestructure 12 onthe interior thereof.

One end of rod 1 is threaded and engages in base member 4. The upper endof rod 1 is provided with a head 1a.. A block 2 of suitable material issecured to the interior wall of plate structure 11 by means of screws 3.The head 1a of rod 1 passes through part 2 fora limited distance but isprevented from disengagement therefrom. The other capacity plate of thecondenser is supplied by plate member 30, shown in section. Plate member30 comprises a partly flattened metallic cylinder or compartment thewalls of which are held in spaced relationship with respect 'to platestructures 11 and 12 and insulated therefrom. Plate member 30 may be inthe form of a box entirely enclosing plate structures 11 and 12. It isdesirable to arrange this box so that it will have sides approximatelyparallel to plate structures 11 and 12. Plate member 30 is supported oninsulating members 25 which are in turn supported from the mainframework of the transmitter. The socket for retaining the anode of aliquid cooled thermionic tube may be positioned in the space 31 andsupported member 40. The anode of the tube would be, in this instance,connected electrically to plate member 30. Certain details of the stopemployed for restricting the downward movement of plate structure 12 aremore fully illustrated in Fig. 2 of the accompanying drawing. Referencecharacters corres ndto those employed in Fig. 1. Plate ructures 11 and12 are illustrated with broken away sections to more clearly `show thisfeature. The effective capacity area of plate structures 11 and 12 isadjustable by means of sliding plate structure 12 over plate structure11. The sliding movement is obtained by the threaded stud and bore shownA part 2, such as a block of insulating material or metal, is secured tothe inner walls of plate structure 11 by means of screws 3. y

-A vertical bore partly through member 2 serves as a guide for rod 1.Near the lower edge of part 2, the diameter of the bore is reduced, fromapproximately that of the terials are employed, both electrically head1a to that of the body of rod 1.l This prevents head la from entirelydisengaging from part 2 and since rod 1 is secured to the base 4 ofplate structure 12, prevents excessive downward movement of platestructure 12. y

Many advantages appear from the arrangement employed in the adjustablecondenser system of my invention. The structure is such asto provide ahighly efficient condenser for use in electricallyv balanced circuitarrangements of high requency transmitting systems. A maximum airinsulation area is provided and the insulating material employed isplaced in such positions where the electrostatic fields are of minimumintensity. The losses experienced when insulating mad an mechanically,make the arrangement of my invention superior to types o high power,high frequency adjustable condensers heretofore employed. Any number ofplate structures similar to members 1l, 12 and 30 lmay be employed. Anynumber of plates either electrically connected in common or insulatedfrom each other may be adjustably controlled by a common mechanicalmeans. I realize that many modifications of my invention are possibleand it is to be understood that my invention shall not be limited by theforegoing specification or by the accompanying drawing but only by thescope of the appended claims.

lVhat I claim as new and desire t'o secure by Letters Patent of theUnited States is as follows:

1. An adjustable condenser comprising in combination a plurality ofplate structures having faces substantially mutually parallel andadapted to telescope the one over the other, a threaded rod in one ofsaid plate structures engaging with a threaded bore provided in anotherof said plate structures for adjusting the relative position of saidplate structures, a traveling rod member associated with said firstnamed plate structure movable through a restricted bore therein forrestricting the relative movement of said plate structures, and astationary outer conductive plate structure having faces substantiallyparallel to faces of said first mentioned plate structures, said outerplate structure being maintained in spaced and insulated relationshipfrom said first mentioned plate structures.

2. An adjustable condenser comprising in combination a plurality ofplate structures electrically connected together and slidably positioneone over the other, Ireans for causing the sliding movement of saidplate structures with respect to each other, means for restricting suchsliding movement to prevent disengagement of said plate structure and astationary outer plate structure spaciall) aaoaeoa positioned andelectrically insulated from said first mentioned plate structures.

3. An adjustable condenser comprising in combination a plurality ofconductive plate structures slidably positioned one over the other,means for actuating the sliding movement of said plate structures withrespect to each other, said means comprising a threaded rod in one ofsaid plate structures coacting with a threaded bore contained in anotherof said plate structures, means for restricting such sliding movement toprevent disengagement of said plate structures, and an outer. stationaryplate structure maintamed 1n spaced relationship with respect to saidfirst mentioned plate structures and having faces substantially parallelto faces of said first mentioned late structures. u

4. An adjustable condenser comprismg 1n combination a plurality ofconductive plate structures slidably positioned one over the other,means for actuating the sliding movement of said plate structures withrespect to each other in balanced relationship, said means comprising aplurality of rotatable rods cooperatively actuated and attached to oneof said plate structures and having a threaded portion coacting withthreaded bores in another of said plate structures, means forrestricting such sliding movement to prevent disengagement of said platestructures, and an outer stationary plate structure maintained in spacedrelationship with respect to said first mentioned plate structures andhaving faces substantially parallel to faces of said first mentionedplate structures.

5. In a condenser system, a pair of plate structures having facessubstantially mutually parallel and adapted to telescope the one overthe other, one of said plate structures comprising two supportingmembers and a conducting sheet comprising a pair of parallel fiatportions each attached to and join'ng said supporting members, athreaded rod in one of said plate structures engaging with a threadedbore provided in the other of said plate structures for adjusting therelative position of said plate structures, a traveling rod memberassociated with said plate structures movable through a restricted boretherein for restricting the relative movement of said plates, and astationary outer conductive plate structure having faces substantiallyparallel to faces of said first mentioned plate structures, said outerplate structure being maintained in spaced and insulated relationshipfrom said first mentioned plate structures.

6. In a condenser system, a pair of plate structures having facessubstantially mutually parallel and adapted to telescope the one overthe other, one of said plate structures comprising two supportingmembers, a llshaped plate member closed at the end opposite saidotherplate structure and open at the end adjacent thereto, said U-shapedmember having its parallel sides attached to and joining said supportingmembers, a threaded rod in one of said plate structures engaging with athreaded bore provided in the other of said plate structures foradjusting the relative structures. l

LUUIS A. GEBHARD.

